Rocker cover gaskets and carb kits arrived this week so this afternoon saw some fettling and just back from a test drive.
Had some fun finding the OT marks for TDC and then after attempting various methods to work out which side was actually at TDC, I rested on the technique of whichever side had the slack on the rockers at TDC was the side which was correct.
There was a bit of vertical movement in the rocker assembly on the intake to the LHS and both intake and exhaust on the RHS so I tightened those up following a couple of youtube guides, torquing up the headbolts to somewhere between 25 and 35 Nm to avoid overtightening. I don't trust my cheap torque wrench at lower numbers so erred on the side of caution. Assume that if it doesn't leak oil, all is well. Will keep an eye on it.
I then sorted the valve clearances, 0.15mm on the intake and 0.20 on the exhaust. The intake needed a tweak on the LHS, was fine on the RHS so a left it be, exhaust was a bit tight on both so backed those off slightly.
Fired the bike up afterwards and all seemed ok after a few coughs and splutters (first start in a week).
I then took the LHS carb off and stripped it down. The main jet was much cleaner than the RHS, I replaced the diaphragm and O rings to the pilot mixture screw and pilot jet as they had failed, also replaced the main jet holder O ring although it looked fine.
I didn't touch the throttle butterfly or choke assemblies as the bike had been idling and running perfectly up to 4000rpm, and dealing with the peening on the butterfly screws didn't appeal. Might need to revisit.
This time I noted the turns from fully closed on the pilot jet and pilot mixture screw. The pilot jet was fully closed, the pilot screw was 1 turn out from closed. On reassembly I set both at 1.25 turns out from closed. Is this correct for the idle jet?
Put everything back together, I'd taken some care with the throttle and choke cables to disturb their positions as little as possible.
Fired the bike up and it idled lumpily - adjusted the LHS throttle stop until it seemed less lumpy and then closed the idle screw until the engine stuttered and backed it out until a regular tickover was reached. Got to a consistent warm tickover of around 1000 - 1100 rpm, which is where the red charge light drops out.
Took the bike out for a run, a warm pleasant evening here in the SE. Immediately it was clear I've upset the low RPM running somehow, the bike was lumpy in traffic under 3000rpm where previously it had been totally smooth. It wouldn't pull smoothly up to higher rpm but at higher throttle openings seemed ok and pulled cleanly to the red line.
Once I got to open roads, and above 3000rpm, it was great. Pulling cleanly and strongly through the gears up to an indicated 70/80mph where I safely could. I didn't have my phone in the tank bag so couldn't check actual speed, I've noticed the speedo significantly over reads, probably more so now I have a diddy 110/90 on the rear.. I had some fun on sweeping A roads for a few miles.
I got onto some dual carriageway and opened up in the top gears, the bike pulled well over the legal limit (if the optimistic speedo is to be believed). Where previously it bogged down, now it was fine to hold rpm over 4000 where ever I set it. Result!
Coming back into the city via Croydon things took a turn for the worse, under 3000rpm the bike was progressively less tractable and refused to rev, running very roughly and feeling like it was running on one cylinder at times. I had some mild backfires and eventually, close to home, the bike backfired loudly and then with just over 100 miles on the trip from the last refuel, conked out.. I set it to reserve and it made it to a petrol station and then home without any further backfiring.
During the ride, at times there was a strong smell of petrol, and there seems to be fuel weeping from the idle screw area of both carbs. This and the low miles until hitting reserve suggests fuel is leaking somewhere. I checked the hoses and there is nothing obvious but running my hand under the carb will produce some petrol on my fingers..
So to summarise my rambling post:
Before messing with valves and carbs, the bike ran perfectly to about 4000rpm and then bogged down at motorway speeds. It would pull cleanly from tickover in 5th gear, even with a pillion, up to 4000 odd rpm or an indicated 60 - 70mph.
Since I've adjusted the valves and stripped and cleaned both carbs, replaced O rings where they have failed and both diaphragms, I now have a bike which was lumpy from tickover to 3000rpm in any gear but once opened up ran well at higher rpm/speeds. After a 40-50 mile loop, returning to urban riding, it ran terribly in traffic.
I expected to need to balance the carbs following fiddling them but I think something more is afoot. I changed the cork gasket on the LHS carb float bowl, I noticed the fit was poor compared to the gasket I removed would this upset anything?
At least the squeak seems to have gone which is a positive
Would welcome thoughts.
edit - from a bit of googling, think I need to screw the idle jets fully closed... will have a tinker tomorrow.
edit again - so popped the float bowls off and in the RHS was sat an idle jet!! So that may explain the poor low speed running on the way home.....refitted and nipped both sides up. Also noticed that the fuel tank filler cap seal has broken... One in one out....
Ade
